The long-range goal of this research is to elucidate molecular mechanisms by which the gonadotrophin LH influences the functions of luteinizing follicles and corpora lutea (CL). The proposed research is based on 2 recent findings. 1. An ovulatory dose of hCG promotes desensitization of the LH-sensitive adenylyl cyclase system to stimulation by LH in preovulatory follicles as well as in CL, and 2. An ovulatory dose of hCG induces changes in the pattern of multiplicity of protein kinases as follicles differentiate into CL, characterized by the appearance of 2 seemingly new species of protein kinase activity. We propose to examine the seemingly new species of protein kinase activities in order to determine: 1. exactly when during the preovulatory or postovulatory time period and by what mechanism do the protein kinases appear, 2. if the luteal-specific prtein kinase is functional in LH-mediated steroidogenesis and/or luteolysis, and 3. whether the presence, activity, and responsiveness of the luteal-specific LH-sensitive adenylyl cyclase and protein kinase enzyme systems are regulated by estrogens, prolactin and/or prostaglandins. The responsiveness of the luteal adenylyl cyclase system to LH, protein kinase activities, and the concentration of nuclear estrogen receptors in CL will be determined. The levels of progestin hormones will also be measured when they are required for a meaningful interpretation of the data.